Understanding and Identifying Crashes on Curves for Safety Improvement Potential in Illinois

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1 Understanding and Identifying Crashes on Curves for Safety Improvement Potential in Illinois Priscilla Tobias, P.E. Mouyid Islam, Ph.D. Kim Kolody, P.E.

2 Optional Agenda Image Title Background Workflow Data Analysis Countermeasures Conclusion

3 Background Horizontal alignment is one of the critical design elements from the standpoint of design consistency. Design speeds for different radii of curves and road geometry along with other factors such as adverse weather, surface conditions, and lighting may disrupt the driver s expectancy and comfort level. Crash rates are about 1.5 to 4 times higher in curved sections than in tangent sections. (Collins et al., 1996; Zegger et al., 1992) References Collins, K.M., and R. A. Krammes Preliminary Validation of Speed-profile Model for Design Consistency Evaluation. Transportation Research Record Transportation Research Board, National Research Council, Washington, D.C., pp Zegger, C. V., J. R. Stewart, F. M. Council, D. W. Reinfurt, and E. Hamilton Safety Effects of Geometric Improvements on 3 Horizontal Curves. Transportation Research Record Transportation Research Board, National Research Council, Washington, D.C., 1992, pp

4 Background This study investigated critical curves with severe injury crashes (the frequency and severity of crashes, namely, fatal (K), incapacitating injury (A-Injury), and non-incapacitating injury (B-Injury)) from the detailed police reported crash database of Illinois. Crash Severity Traditional Injury Scale Levels Fatal Crash K Severe Injury Crash Incapacitating Injury Crash A Non-incapacitating Injury Crash B Possible Injury Crash C Non-severe Injury No Injury Crash (PDO) O Crash 4

5 Work-flow for Data Sample Illinois Crash Database (Analysis Period: ) Filtering Crashes coded on Curve Segments (Curve level, Curve on hillcrest, and Curve on grade) Ranking Segments using Crash Severity Weighing Scheme (K=25, A=10, B=1) Preliminary Analysis on Factors associated with K, A, and B Crash Frequency for Assigned Segments Proposing Countermeasures for Consideration based on Predominant Crash Factors 5 Evaluating the Effectiveness of the implemented Countermeasures Future Work

6 Data Analysis Major Highlights Crash data over a 5-year period (2007 to 2011) indicated 80,865 curves crashes with an average of 5.2% of total crashes occurred on curves annually. 22.4% (18,122 out of 80,865) severe crashes (KAB) occurred on these identified curve crashes. Severe crash (KAB) weighing scheme identified 4,836 crashes (top 70 curves per district) occurred approximately in 600 curves. 10% severe crashes (KAB) occurred on the curved segments that represents 30% of all road departure crashes. 6

Study Area: Illinois Analysis Year: 2007

7 Study Area: Illinois Analysis Year: , Sample Size = 4,836 Injury Severity Levels 2% 14% 51% 27% 5% 7 K Injury Crash A Injury Crash B Injury Crash C Injury Crash PDO Crash

8 Spatial Characteristics 8

9 Curve Crash Frequency Distribution by Functional Class, , Illinois Crash Frequency 0% 5% 10% 15% 20% 25% 30% Interstate (PAS) 25% Other Principal Arterial (PAS) 21% Minor Arterial (Non-Urban) 8% Major Collector (Non-Urban) 17% Minor Collector (Non-Urban) 2% Local Road or Street (Non-Urban) 5% Freeway and Expressway (Urban Only) (PAS) 0% Minor Arterial (Urban) 11% Collector (Urban) 6% Local Road or Street (Urban) 5% 9

10 Curve Crash Severity Distribution by Functional Class, , Illinois Crash Frequency Interstate (PAS) Other Principal Arterial (PAS) Minor Arterial (Non-Urban) Major Collector (Non-Urban) Minor Collector (Non-Urban) Local Road or Street (Non-Urban) Freeway and Expressway (Urban Only) (PAS) Minor Arterial (Urban) Collector (Urban) Local Road or Street (Urban) 10 Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injury Crash

11 Curve Crash Severity Distribution by Area and Route Type, , Illinois Curve Crash Severity Distribution by Urban and Rural Area Urban Rural Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injury Crash Curve Crash Severity Distribution by State and Local Route State Local Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injury Crash

12 Curve Crash Severity Distribution by Area Type and Number of Vehicles Involved, , Illinois Crash Frequency Fatal Crash Rural Urban No Injury Crash C Injury Crash B Injury Crash A Injury Crash Rural Urban Rural Urban Rural Urban Rural Urban 12 Single-Vehicle Multi-Vehicle

13 Curve Crash Frequency and Severity Distribution by Crash Types, , Illinois Crash Frequency Fixed object Overturned Rear end Sideswipe same direction Animal Other non collision Sideswipe opposite direction Head on Angle Turning Other object Parked motor vehicle Pedestrian Pedalcyclist 13 Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injury Crash

14 Curve Crash Frequency and Severity Distribution by Area Type and Crash Types, , Illinois Crash Frequency C Injury Crash B Injury Crash A Injury Crash Fatal Crash Rural Urban Rural Urban Rural Urban Rural Urban Fixed object Overturned Rear end Sideswipe same direction Animal Other non collision Sideswipe opposite direction Head on Angle Turning Other object Parked motor vehicle Pedestrian Pedalcyclist No Injury Crash 14 Rural Urban

15 Curve Crash Severity Distribution by Traffic Volume (vehicle per day), , Illinois Traffic Volume (vehicle per day) Crash Frequency Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injury Crash 15

16 Environmental Characteristics 16

17 Curve Crash Frequency Distribution by Lighting Condition, , Illinois Crash Frequency 0% 10% 20% 30% 40% 50% 60% Daylight 54% Darkness 27% Darkness, Lighted Road 14% Dawn 2% Dusk 2% 17

18 Curve Crash Severity Distribution by Lighting Condition, , Illinois Crash Frequency Daylight Darkness Darkness, Lighted Road Dawn Dusk Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injury Crash 18

19 Curve Crash Frequency Distribution by Weather Condition, , Illinois Crash Frequency 0% 10% 20% 30% 40% 50% 60% 70% Clear 64% Rain 21% Snow 9% Fog/Smoke/Haze 2% Sleet/Hail 1% Other 1% Unknown 1% Severe Cross Wind 0% 19

20 Curve Crash Severity Distribution by Weather Condition, , Illinois Crash Frequency Clear Rain Snow Fog/Smoke/Haze Sleet/Hail Other Unknown Severe Cross Wind Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injury Crash 20

21 Temporal Characteristics 21

22 Curve Crash Frequency and Severity Distribution by Time of Day, , Illinois 12:00 AM 1:00 AM 2:00 AM 3:00 AM 4:00 AM 5:00 AM 6:00 AM 7:00 AM 8:00 AM 9:00 AM 10:00 AM 11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM 7:00 PM 8:00 PM 9:00 PM 10:00 PM 11:00 PM Crash Frequency Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injuy Crash

23 Curve Crash Frequency and Severity Distribution by Day of Week, , Illinois Crash Frequency Saturday Sunday Weekend Monday Tuesday Wednesday Thursday Friday 23 Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injury Crash

24 Curve Crash Frequency and Severity Distribution by Month of Year, , Illinois Crash Frequency January February March April May June July August September October November December Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injury Crash 24

25 Drivers Characteristics 25

26 Curve Crash Frequency and Severity Distribution by Gender, , Illinois Crash Frequency Male Female Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injury Crash 26

27 Curve Crash Frequency and Severity Distribution by Age Group, , Illinois Crash Frequency Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injury Crash 27

28 Factors Identified as Primary Cause by the investigating police officers at crash scenes 28

29 Curve Crash Frequency Distribution by Factors, , Illinois Crash Frequency 0% 2% 4% 6% 8% 10% 12% 14% 16% 18% 20% Exceeding Safe Speed for Conditions 17.7% Failing to reduce speed / yield to Right of Way 15.2% Weather 13.5% Improper lane usage/ backing/ overtaking/ turning Unable to Determine/NA 10.5% 10.1% Impaired driving (alcohol, drugs) 7.9% Animal Driving Skills/Knowledge/Experience 4.2% 6.2% Distraction from inside/outside, electronic device Exceeding Speed Limit Physical Condition of Driver Equipment vehicle condition Following Too Closely Evasive Action (Animal, Object, Non-Motorist) Road Engineering/Surface/Marking Defects Operating vehicle reckless Driving on Wrong Side/Wrong Way Disregarding Road Markings/ STOP Signs/ Yield Signs/ Signals Road Construction/Maintenance Vision Obscured Passing Stopped School Bus 2.4% 2.4% 1.8% 1.6% 1.4% 1.3% 1.1% 1.1% 0.6% 0.6% 0.3% 0.1% 0.0% 29

30 Curve Crash and Severity Distribution by Factors, , Illinois Crash Frequency Exceeding Safe Speed for Conditions Failing to reduce speed / yield to Right of Way Weather Improper lane usage/ backing/ overtaking/ turning Unable to Determine/NA Impaired driving (alcohol, drugs) Animal Driving Skills/Knowledge/Experience Distraction from inside/outside, electronic device Exceeding Speed Limit Physical Condition of Driver Equipment vehicle condition Following Too Closely Evasive Action (Animal, Object, Non-Motorist) Road Engineering/Surface/Marking Defects Operating vehicle reckless Driving on Wrong Side/Wrong Way Disregarding Road Markings/ STOP Signs/ Yield Signs/ Signals Road Construction/Maintenance Vision Obscured Passing Stopped School Bus 30 Fatal Crash A Injury Crash B Injury Crash C Injury Crash No Injury Crash

31 Low-cost Countermeasures and Feedback 31

32 Selection Criteria for Countermeasures Crash Types Angular Animal-related Rear-end Head on Turning Over-turning Fixed-object Side-swipe (same direction) Side-swipe (oppositedirection) Weather Conditions Rain Snow Sleet/Hail Fog/ Smoke/ haze Lighting Conditions Dark Darkness Lighted Road Dawn Dusk 32

33 Framework for Low-cost Countermeasures Selection Possible Countermeasures (Low-cost) for Consideration Crash Type Crash Attributes Weather Conditions Lighting Conditions Install shoulder rumble strip Fixed object, Over-turning NA NA Install center line rumble strip Increase shoulder width Improve skid resistance of pavement Head-on, Sideswipe opposite direction Angular, Rear-end, Sideswipe same direction, turning, Pedestrians, Pedalcyclists NA NA NA NA NA Rain, sleet/hail NA Install lighting NA NA Install delineating chevron(s) Fixed object, Over-turning NA Dark, darknesslighted road, dawn, dusk Install advance warning sign Pedestrians, Pedalcyclists Snow, fog/smoke/haze NA 33 References McGee, H.W., and F. R. Hanscom, Low-Cost Treatments for Horizontal Curves Safety, Report No: FHWA-SA , FHWA. NCHRP Report 500, Guidance for Implementation of AASHTO Strategic Highway Safety Plan, Volume 7: A Guide for Reducing Collisions on Horizontal Curves, Transportation Research Board, Washington D.C., 2004.

34 Improvements Feedback Curve Safety All nine districts sent us the response forms with the improvement status of the top 50 curves in their district jurisdictions. All nine districts considered the proposed low-cost countermeasures. Chevrons Widen shoulder Interchange relocation Rumble stripes Lighting Warning signs Resurfacing Bituminous shoulder Superelevation High friction surface 34

35 Goal Settings for Fatalities of Curve-related Crashes Fatalities Fatalities per HMVMT Yr Rolling Avg. Number of Fatalities 5-Yr Rolling Avg. Fatality Rate (per HMVMT)

36 Conclusion The predominant crash types involving single vehicle running off, overturning, and hitting fixed roadside objects result in severe injury crashes. Most of severe crashes occurred on state routes in rural settings. Improper lane use and exceeding safe speed for conditions are major contributing factors on severe crashes on curves. It is a data-driven, science-based approach for the statewide screening process to identify critical curves for safety potential improvement. Crash Modification Factors for the Countermeasures at the sites Goal Setting as per TZD under MAP-21 (HSIP Online Reporting) 36

37 Thank You Comments Questions Suggestions Contact:

Traffic Accident Statistics

2000 Missouri State Highway System Traffic Accident Statistics Missouri State Highway System Traffic Accident Statistics Table of Contents Subject Chapter 1: Statewide Traffic Accident Statistics, Introduction